Using a systemic perspective to treat survivors of incest elicits thecontroversial question of whether to involve the perpetrator inthe therapy process. Ethically, the therapist has a responsibilityto ensure that the therapeutic process will do no harm to theclient; therefore, involving the perpetrator may be contraindicatedin some circumstances. Therapists may feel torn between deter-mining what the most ethical practice is. This determination isaffected by a wide variety of factors, and requires clinical judg-ment once these factors are understood. The article proposes theIncest-Perpetrator Involvement Checklist to guide therapists throughthe relevant issues that should be addressed prior to approving theperpetrator’s inclusion in conjoint therapy with the survivor.